Robert Pershing Wadlow (February 22, 1918 – July 15, 1940), also known as the Alton Giant and the Giant of Illinois. He was born and raised in Alton, Illinois, a small city near St. Louis, Missouri. Wadlow was a man who was the tallest person in recorded history for whom there is irrefutable evidence. He is the tallest verified American. Wadlow's height was 8 ft 11 in (2.72 m) while his weight reached 439 lb (199 kg) at his death at age 22. His great size and his continued growth in adulthood were due to hypertrophy of his pituitary gland, which results in an abnormally high level of human growth hormone (HGH). Even by the time of his death, there was no indication that his growth had ended.